Protocol
The player URL is given (via get, not post) the current board state, the colour it's playing as, and the ply. It returns in the body the new board state and move it made. Yes, I know it shouldn't return the new state, but I don't
feel like writing validation code right now. We're all honest, right? Specifically the 'get' variables passed are:

"board" : A string of 64 characters made of the letters e, b, and w. These represent empty, black, and white.

"player" : Either "black" or "white".

"ply" : An integer bigger than 0.

In response it should print out two strings separated by a space. The first should be a 64 character string with the new board state consisting of those same three characters, 'e', 'b', and 'w'.
The second string should be the move it made using the 'a to h' and '1 to 8' axes you see on the board. For example, a8 is the top left corner. If a move can't be made, the string should be "pass".